1. Technical Field
This application relates to UMTS (Universal Mobile Telecommunications System) in general, and in particular to a method and apparatus for calculating an initial transmission power in universal mobile telecommunications system user equipment.
2. Description of the Related Art
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In a typical cellular radio system, mobile user equipment (UE) communicates via a radio access radio network (RAN) to one or more core networks. User equipment (UE) comprises various types of equipment such as mobile telephones (also known as cellular or cell phones), lap tops with wireless communication capability, personal digital assistants (PDAs) etc. These may be portable, hand held, pocket sized, installed in a vehicle etc and communicate voice and/or data signals with the radio access network.
The radio access network covers a geographical area divided into a plurality of cell areas. Each cell area is served by at least one base station, which may be referred to as a Node Bs. Each cell is identified by a unique identifier which is broadcast in the cell. The base stations communicate at radio frequencies over an air interface with the UEs within range of the base station. Several base stations may be connected to a radio network controller (RNC) which controls various activities of the base stations. The radio network controllers are typically connected to a core network.
UMTS is a third generation public land mobile telecommunication system. Various standardization bodies are known to publish and set standards for UMTS, each in their respective areas of competence. For instance, the 3GPP (Third Generation Partnership Project) has been known to publish and set standards for GSM (Global System for Mobile Communications) based UMTS, and the 3GPP2 (Third Generation Partnership Project 2) has been known to publish and set standards for CDMA (Code Division Multiple Access) based UMTS. Within the scope of a particular standardization body, specific partners publish and set standards in their respective areas.
Consider a wireless mobile device, generally referred to as user equipment (UE), that complies with the 3GPP specifications for the UMTS protocol. The 3GPP 25.331 specification, v.3.14.0, referred to herein as the 25.331 specification, addresses the subject of the Radio Resource Control (RRC) protocol specification. The 3GPP 25.304 specification, v.3.14.0, referred to herein as the 25.304 specification, addresses the subject of UMTS User Equipment (UE) procedures in idle mode and procedures for cell reselection in connected mode between the UMTS Terrestrial Radio Access Network (UTRAN) and the UE.
When UEs initiate uplink communication with the UTRAN, there are two common channels for transmission: RACH (Random Access Channel) and CPCH (Common Packet Channel). However, as otherwise commonly utilised in UMTS transmissions, closed loop power control can not be used since it cannot be established prior to transmission.
Clause 8.5.7 of the 25.331 standard describes an open loop power control method including calculation of PIP (preamble initial power) for such transmissions withPIP=IE(1)+IE(2)+IE(3)−M(1),where the IEs (1-3) (information elements 1-3) are read from broadcast system information, and M(1) is measured. Considering the communication system in terms of a standard radio access protocol stack, M(1) is measured in a lowest (physical) layer, IEs (1-3) read in higher layers, M(1) sent to the higher layers where PIP is calculated, and PIP sent to L1 for use in transmission. The transmission power is then “ramped up” in steps until either a response is received, or the ramping process completes.
PIP must be calculated prior to transmission, or when any of the broadcast values change, and PIP submitted to L1.
There are proposed strategies for dealing with PIP calculation.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of an apparatus and method for calculating an initial transmission power.
The same reference numerals are used in different figures to denote similar elements.